Subject: [Sip] Keeping session data in SIP messages?

From: Ahti Legonkov <[email-masked]>
Date: Fri, 15 Dec 2006 20:28:53 +0200

Hello!

I am writing a load balancing SIP proxy and would like to keep it as
simple as possible, ie. I would like to avoid using any databases.

Currently I have come up with the following solution:

When first INVITE arrives, calculate branch parameter, determine the
server to forward the message to, store the relation between branch
and server name in database. When another message in this session
arrives (the same branch parameter of Via header) the server name is
looked up from database and the message is forwarded to that server.

Can I put some header or parameter for some header in the message
that client would be required to include in the next request message
it sends out during the session?

Thanks!

--
Ahti Legonkov

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From: Paul Kyzivat <[email-masked]>
Date: Fri, 15 Dec 2006 14:05:05 -0500

> it sends out during the session?

Its not clear to me why you need to do anything.

If the server is the UAS, then it will return a Contact header with the 
uri to be used for additional requests in the session. If your proxy is 
even involved in the subsequent messages, then it will simply forward to 
that address, which will be in the R-URI.

If the server you selected is a proxy, and if it wants to be involved in 
subsequent in-dialog requests, then it can Record-Route. And if *your* 
proxy wants to be in subsequent requests in the dialog, then it also 
should Record-Route.

What more is required here?

	Paul

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From: Ahti Legonkov <[email-masked]>
Date: Fri, 15 Dec 2006 23:42:45 +0200

> proxy wants to be in subsequent requests in the dialog, then it also 

There had to be a simple and elegant solutiond and this is it. Thanks!

--
Ahti Legonkov